Synthesis and Structure Resolution of RbLaF4

The synthesis and structure resolution of RbLaF4 are described. RbLaF4 is synthesized by solid-state reaction between RbF and LaF3 at 425 degrees C under a nonoxidizing atmosphere. Its crystal structure has been resolved by combining neutron and synchrotron powder diffraction data refinements (Pnma, a = 6.46281(2) angstrom, b = 3.86498(1) angstrom, c = 16.176:29(4) angstrom, Z = 4). One-dimensional Rb-87, La-139, and F-19 MAS NMR spectra have been recorded and are in agreement with the proposed structural model. Assignment of the F-19 resonances is performed on the basis of both F-19-La-139 J-coupling multiplet patterns observed in a heteronudear DQ-filtered J-resolved spectrum and F-19-Rb-87 HMQC MAS experiments. DFT calculations of both the F-19 isotropic chemical shieldings and the Rb-87, La-139 electric field gradient tensors using the GIPAW and PAW methods implemented in the CASTEP code are in good agreement with the experimental values and support the proposed structural model. Finally, the conductivity of RbLaF4 and luminescence properties of Eu-doped LaRbF4 are investigated.